Method of marking materials subject to elongation employing heated dies

ABSTRACT

The disclosure is directed to the method of marking materials subject to elongation as by stretching. The method comprises the steps of placing in a surface of the material at least one groove in a direction generally transverse to the direction of elongation of the material and applying to the groove coloring material in such a manner that the coloring material adheres to the sidewalls of the groove, thus permitting the coloring material to elongate with the material without breaking, flaking or separating from the sidewalls of such groove. A first method permits the forming of the groove and adding the coloring material thereto by the use of a colored metallic foil inserted between a heated die and the material itself. The heated die forming the groove causes the adherence of the colored foil to the groove walls. According to other methods the grooves may be preformed as by use of cold dies or by premolding the material to have the groove within it and then coloring the groove by means of stamping through a colored foil or painting.

United States Patent I [72] Inventor Richard Stephen Schwartz Union Township, Union, NJ. 21 Appl. No. 825,912 [22] Filed May 19, 1969 [45] Patented Aug. 17, 1971 [73] Assignee Thomas & Betts Corporation Elizabeth, NJ.

[54] METHOD OF MARKING MATERIALS SUBJECT TO ELONGATION EMPLOYING HEATED DIES 7 Claims, 6 Drawing Figs.

[52] US. Cl 101/32, 101/426, 101/31 [51] Int. Cl B441: 1/24, B41c 1/02 [50] Field of Search 101/32, 8, 9, 10, ll, 25, 27, 31, 426 GL; 197/66 [56] References Cited UNITED STATES PATENTS 904,912 11/1908 Allison 101/32 2,370,416 2/1945 Polley.... 101/426 G.L. 2,524,690 lO/l950 Worde... 101/426 G.L. 2,645,178 7/1953 Brainard eta v r 101 401.1

2,838,416 6/1958 Babiarz et a1.

Primary ExaminerWilliam B. Penn Assistant ExaminerE. M. Coven Att0rney David Teschner ABSTRACT: The disclosure is directed to the method of marking materials subject to elongation as by stretching. The method comprises the steps of placing in a surface of the material at least one groove in a direction generally transverse to the direction of elongation of the material and applying to the groove coloring material in such a manner that the coloring material adheres to the sidewalls of the groove, thus permitting the coloring material to elongate with the material without breaking, flaking or separating from the sidewalls of such groove. A first method permits the forming of the groove and adding the coloring material thereto by the use of a colored metallic foil inserted between a heated die and the material itself. The heated die forming the groove causes the adherence of the colored foil to the groove walls. According to other methods the grooves may be preformed as by use of cold dies or by premolding the material to have the groove within it and then coloring the groove by means of stamping through a colored foil or painting.

METHOD OF MARKING MATERIALS SUBJECT TO ELONGATION EMPLOYING HEATED DIES BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to the field of marking materials subject to elongation as by stretching, such as with plastic bundling straps. Such straps are initially planar members having a given length. The strap is placed about a plurality of articles, such as conductors, in order to form a bundle and the strap is then drawn tightly about the individual conductors in order to form a tightly united bundle. In so tightening the strap the material of the strap itself is generally elongated.

2. Description of the Prior Art In prior art techniques, for marking materials subject to elongation as by stretching, the common practice is to hotstamp a foil of colored material to the top surface of the material. However, it was found that when the material was subjected to elongation, as by stretching, the colored foil, having a different modulus of elasticity than that of the plastic material, would stretch at a different rate causing the foil to be cracked in various places and to flake off of the surface of the plastic material. The degree of breakage, and flaking, of the foil from the surface of the material was dependent upon the degree of elongation to which the material itself was subjected. Another technique employed is the surface painting of the material, however, such surface painting also resulted in cracking, or flaking off, of the surface paint due to different moduli of elasticity.

SUMMARY OF THE INVENTION The present invention seeks to overcome the difficulties noted above with respect to prior art marking techniques of marking either by surface painting or the adherence of a colored metallic foil thereto. This is achieved by providing a coloring method for marking such materials wherein the marking material is not destroyed by the subsequent elongation of the material. The method is practiced by the formation of one or more grooves along the surface of the material to be marked in a direction generally transverse to the direction of elongation of the material. These grooves will take generally a V-shape, or U-shape and will have placed therein a coloring material such that it will adhere to the walls of the groove. By this construction the differences in moduli of elasticity of the material, and of the coloring agent, can be accommodated without the destruction of the coloring agent within and upon the material. In a first technique the coloring material in the form of a metallic foil is inserted between the surface of the material to be colored and a hot die having provision to make properly shaped grooves in the surface of the material. The hot die is then impressed through the foil into the-surface of the material to be marked carrying with it portions of the colored foil and causing the same to adhere to the walls of the grooves formed by the die. In other methods disclosed, the grooves may be preformed as by premolding the grooves into the material or may be cold-formed after the material has been completed and then the coloring material is added as by painting or by hot-stamping through a metallic colored foil. It is therefore an object of this invention to provide an improved method of marking materials subject to elongation as by stretching and which preserves such marking after such elongation.

It is another object of this invention to provide an improved method of marking a material subjected to elongation as by stretching by providing at least one groove in the surface thereof and having a coloring material adhering to the walls of such formed groove.

It is still another object of this invention to provide a method for marking materials subjected to elongation by forming at least one groove therein and introducing a coloring agent into said groove and causing said coloring agent to adhere to the walls thereof by use of a heated die impressed upon such material through a foil of colored material.

It is still another object of this invention to provide a method for marking materials subjected to elongation as by stretching, employing the use of at least one preformed groove in the surface of the material and introducing a coloring agent by painting or the hot-stamping of a metallic colored foil to said groove whereby the coloring material is caused to adhere to the sidewalls of said groove.

Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose,- by way of example, the principles of the invention and the best modes which have been contemplated for carrying them out.

BRIEF DESCRIPTION OF THE DRAWING In the figures in which similar elements are given similar reference characters:

FIG. 1 is a perspective view of a plastic article bundling strap which may be subjected to elongation as by stretching and illustrating the marking method disclosed herein.

FIG. 2 is a side elevation of a portion of the plastic article bundling strap of FIG. 1 together with the apparatus employed to accomplish the marking method disclosed herein.

FIG. 3 is a side elevation of a portion of a plastic article bundling strap as shown in FIG. 2 after completion of the first portion of the method described herein.

FIG. 4 is a side elevation of a portion of a plastic article bundling strap as shown in FIG. 2 illustrating the appearance of the colored material with respect to such plastic article bundling strap after completion of the method described herein.

FIG. 5 is a top plan view of a portion of a plastic article bundling strap as illustrated in FIG. 1 showing grooves extending perpendicular to the direction of elongation.

FIG. 6 is a top plan view of a portion of a plastic article bundling strap similar to that shown in FIG. 1 and showing the grooves extending in a direction 45 to the direction of elongation of the plastic article bundling strap.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIG. 1 there is shown a plastic article bundling strap 10 having a strap body portion '12 which will be placed about a plurality of individual articles, such as conductors, to be grouped into a bundle. The plastics generally employed for use in such bundling straps 10 are broadly identified as nonmelt formable thermal plastics and include materials such as nylon. These plastic materials can be worked or formed in a nonmelt condition and are stretchable. They will recover or show plastic memories below their elastic limits but elongate when subjected to stretching forces above their elastielimits. Excessive forces above their yield point may cause the plastic straps 10 to break. The tail end 14 of the strap 10 will be inserted through an aperture 16 in the head end portion 18 and a locking member 20 will be employed to retain the strap body portion 12 within the head end portion 18. Further, to insure a tight bundle, the strap body portion 12 will be drawn tightly about the articles to be bundled by applying stresses in the directions shown by the arrows 22 and causing elongation along the line described by the arrows 22.

Previous markings to identify such cables, employing either a paint, or metallic foil, were destroyed by such elongation.

Tuming'now to FIG. 2 there is illustrated a first technique for carrying out the marking method of the invention. The bundling strap 10 has a colored metallic foil 24 placed thereover and a die'26 placed such as to sandwich the foi 24 between the die '26 and the bundling strap 10. Only the colored metallic foil layer 24 has been shown for the sake of simplicity. Actually, a laminated colored material carrier strip is employed which has a backing layer of MYLAR or similar material and a colored material layer such as the colored metallic foil 24. The backing layer provides a convenient web for advancing the foil 24 to its desired position and for removing any excess foil not required by the marking. The mechanisms for advancing the colored material carrier into and out of the die 26 area are well known and are not shown.

Different types of foils 24 will be employed depending upon the color to be used. These foils 24 will have different moduli of elasticity but in all cases will have a modulus of elasticity different than the material of strap 10. The die 26 has a plurality of protrusions28 in order to form V-shapecl grooves within the surface of the bundling strap as will be described. Although the protrusions 28 are shown to be generally V-shaped they may be U-shaped or any other convenient shape as is desired. The die 26 will generally be preheated and then forced through the foil 24 into the surface of the bundling strap 10. If the die 26.were immediately removed and the strap 10 could be inspected it would be found that a plurality of V-grooves 30 had been formed with segments of color foil 32 adhering to the walls of the V-grooves 30. However, as the stresses are relieved and the strap 10 cooled down, the shape of the grooves 30 relax from their V-shaped and will generally be U-shaped as is shown in FIG. 4 by the grooves 30'. The reason for the relaxation of the grooves 30 from their V-form to the generally U-shape 30 is due to the plastic memory of the material of the strap 10 and its attempt to return to its initial condition once the distorting force of the die 26 is removed. The degree of relaxation and thus the distortion of the V-grooves 30 to the V-shaped grooves 30 will depend upon the type of material employed for the strap 10, its hardness, its moisture content, the force applied by the die 26, the shape of the die 26,the dwell time of the die 26 upon the strap 10, thepreheat temperature of die 26, the uniformity of the heating of die 26, the elasticity and thickness of foil 32 and the desired depression depth of the grooves 30. Depending upon the conditions set forth above an almost V- shaped groove can be maintained or a smooth continuous U- shaped groove can be attained, or if desired a broad U-shaped groove approaching or actually reaching a rectangular shape may be employed. In most instances the resulting U-shaped groove is a rounded V-shape or generally U-shaped groove. The clear U-shaped grooves 30 of FIG. 4 represent a somewhat idealized form of the relaxed groove 30' for the sake of clarity and to simplify the description. By the useof a foil 32 which is somewhat inelastic, or by the use of a die 26 whose protrusions 28 are somewhat rounded, or by control of the pressure or temperature to which the die 26 is preheated, the foil 32 will only be permitted to adhere to the sidewalls of the grooves 30 and when they relax to the U-shaped grooves 30' the segments of colored foil 32' will also take on the generally U-shape. If, however, a very sharp protrusion 28 is employed and the foil 32 is very elastic, adherence of the foil 32 to the grooves 30 will be complete and some tearing along the root of theV of the foil 32 will occur when the strap 10 relaxes. The amount of separation between the resulting portions of the foil 32 in the grooves 30 will be small and for all purposes the viewer will see a continuous band of color and will not notice the minute break. Due to this particular configuration of the foil segments 32' with respect to the grooves 30' the elongation of the strap 10, as by stretching, permits more closely matching of the elongation of the foil segments 32 with the plastic of the strap 10 and will minimize any breaking of the foil segments 32', at least within the range of the plastic limit of the strap 10.

As shown in FIG. 5, grooves 30' may be placed in a direction perpendicular to the direction of elongation of the strap 10 and as shown in FIG. 6 may be placed at an angle of approximately 45 to the direction of the elongation. These positions of the grooves 30 have been described only for the purpose of illustration and are not considered limiting in that any desired angle of the groove, with respect to direction of elongation, may be employed.

In addition to the hot-stamping to form the grooves and cause adherence of the coloring material to such grooves simultaneously, the grooves 30 may be preformed by molding as shown in FIG. 1 or may be cold-stamped into the strap body portion 12 by use of a cold die similar to die 26 of FIG. 2 or hot-stamped by use of a heated die26 but without the inclusion of the foil :24. The coloring material may then be introduced by painting, as for example by brushing, rolling,

dipping or silk screening or by the later application of foil segments by the use of a hot die as was described above with respect to FIG. 2.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiments, it will be understood that various omissions and substitutions and changes of the form and details of the devices illustrated and in their operation may be made by those skilled in the art, without departing from the spirit of the invention.

The embodiments of the invention in which I claim an exclusive property or privilege are defined as follows:

1. The method of marking a stretchable nonmelt formable thermal plastic material subject to elongation comprising of the steps of: placing said material on a suitable support; covering at least a portion of the exposed surface of said material with a laminated colored material carrier having a colored material layer and a carrier layer, said colored material and said plastic material such having a different modulus of elasticity; heating a substantially V-shaped die to a predetermined temperature; impressiri'g said heated die into said laminated colored material carrier and said material to form at least one substantially V-shaped groove in said material in a direction generally transverse to the direction of elongation; removing said heated die and permitting said material to relax from the stresses produced by impressing said heated die into said material; whereby said colored material is caused to adhere only along the length of the walls of said groove when said heated die is withdrawn from said material and said material is stretched.

2. The method, as defined in claim 1, wherein said colored material layer of said laminated colored material carrier is a foil.

3. The method, as defined in claim 1, wherein said groove is V-shaped.

4. The method, as defined in claim 1, wherein said groove is U-shaped.

5. The method, as defined in claim 1, wherein said groove extends in a direction perpendicular to the direction of elongation of said material.

6. The method, as defined in claim 1, wherein said groove extends in a direction at 45 to the direction of elongation of said material.

7. The method of marking a stretchable nonmelt formable thermal plastic material subject to elongation comprising the steps of: placing said material on a suitable support; impressing a substantially V-shaped die into said material to form at least one substantially V-shaped groove in said material in a direction generally transverse to the direction of elongation covering at least a portion of the exposed surface of said material with a laminated colored material carrier having a colored material layer and a carrier layer, said colored material and said plastic material each having a different modulus of elasticity; said colored material covering said groove; heating said substantially V-shaped die to a predetermined temperature; aligning said die with said substantially V- shaped groove in said material; impressing said heated die into said laminated colored material, causing said laminated color material to engage the sidewalls of said V-shaped groove; and removing said heated die and permitting said material to relax from the stresses produced by impressing said heated die against said material; whereby said colored material is caused to adhere only along the length of the walls of said groove when said heated die is withdrawn from said material and said material is stretched. 

1. The method of marking a stretchable nonmelt formable thermal plastic material subject to elongation comprising of the steps of: placing said material on a suitable support; covering at least a portion of the exposed surface of said material with a laminated colored material carrier having a colored material layer and a carrier layer, said colored material and said plastic material such having a different modulus of elasticity; heating a substantially V-shaped die to a predetermined temperature; impressing said heated die into said laminated colored material carrier and said material to form at least one substantially Vshaped groove in said material in a direction generally transverse to the direction of elongation; removing said heated die and permitting said material to relax from the stresses produced by impressing said heaTed die into said material; whereby said colored material is caused to adhere only along the length of the walls of said groove when said heated die is withdrawn from said material and said material is stretched.
 2. The method, as defined in claim 1, wherein said colored material layer of said laminated colored material carrier is a foil.
 3. The method, as defined in claim 1, wherein said groove is V-shaped.
 4. The method, as defined in claim 1, wherein said groove is U-shaped.
 5. The method, as defined in claim 1, wherein said groove extends in a direction perpendicular to the direction of elongation of said material.
 6. The method, as defined in claim 1, wherein said groove extends in a direction at 45* to the direction of elongation of said material.
 7. The method of marking a stretchable nonmelt formable thermal plastic material subject to elongation comprising the steps of: placing said material on a suitable support; impressing a substantially V-shaped die into said material to form at least one substantially V-shaped groove in said material in a direction generally transverse to the direction of elongation covering at least a portion of the exposed surface of said material with a laminated colored material carrier having a colored material layer and a carrier layer, said colored material and said plastic material each having a different modulus of elasticity; said colored material covering said groove; heating said substantially V-shaped die to a predetermined temperature; aligning said die with said substantially V-shaped groove in said material; impressing said heated die into said laminated colored material, causing said laminated color material to engage the sidewalls of said V-shaped groove; and removing said heated die and permitting said material to relax from the stresses produced by impressing said heated die against said material; whereby said colored material is caused to adhere only along the length of the walls of said groove when said heated die is withdrawn from said material and said material is stretched. 